In-Detail Guide on How to Measure Your Bathtub Inside and Outside

Last updatedLast updated: April 02, 2021
Bathroomer is reader-supported. We may earn a commission through products purchased using links on this page. Learn more about our process here

Bathtubs are available in different shapes, sizes, and styles. But whether you are looking to install an alcove bathtub or a drop-in bathtub, you have to think about how it fits into the bathroom space. The bathtub is arguably the most important element of the bathroom. It isn’t just functional. But it is also the centerpiece of the bathroom. Therefore, you must choose the right one.

Before you make a pick, you must consider the space available and the bathtub’s size you want to buy. To get the right size, you should know how to measure a bathtub. If that seems challenging, do not fret because we have taken the time to consider the best ways to get an accurate measurement of a bathtub.

This post will come in pretty handy for anyone looking to change their bathtub or install a new one. We consider the different types of bathtubs available and how to measure each type.

Types of Bathtubs

In-Detail Guide on How to Measure Your Bathtub Inside and OutsideThere are numerous types of bathtubs on the market right now. In this section, we consider some of the most popular options that you have right now. With that in mind, let’s get to the common options.

Freestanding bathtub

This is a common type of bathtub, and many people recognize it immediately they lay eyes on it. As the name implies, these tubs are made as freestanding models that are not attached to the wall. There are several types of freestanding tubs, and inflatable hot tubes are also one type of these models.

Because of the design, most users install these tubs in the bathroom’s center. It looks great and classy.

If you are choosing this type of tub, then you must have enough space in the bathroom. They are usually big units that will not sit well in a small bathroom.

One of the best things about this unit is that you have more flexibility in choosing the size. As long as you have plenty of bathroom space, you don’t have to worry about the bathtub’s exact measurements.

Alcove bathtubs

The alcove is, as the name implies, a spot that is bounded by a trio of walls. This is often how the alcove bathtub is positioned in a bathroom. If the bathroom has a narrow design, then the tub is usually situated so that the two longer walls of the space are the ends of the tub, and the back wall closes the tub. In such a design, the walls form an alcove.

You need a 6 x 6 room at least to enjoy the alcove bathtub in terms of measurements.

For larger bathroom sizes, you have a wider range of choices when setting up the alcove tub. These tubs are usually between 4 ½ to 6 feet long with a width of between 30 to 36″.

Drop-in Bathtubs

These tubs come with a similar design to the alcove models. However, there are certain differences. For one, drop-in bathtubs come with a bathtub shell and do not have finished sides.

Installation is similar to the alcove bathtub installation. You could also decide to have them installed against a wall.

According to users, one of the best models is the American Standard deep soaking tub with its 36″ depth.

One of the downsides of this type of bathtub is that installation is more complex than other bathtubs.

Undermount bathtubs

These tubs are like drop-in tubs. However, they have a deck where they are fitted on. These decks are made of different materials like stone or tile.

One benefit of this type of tub is the classy appearance that it has. The downside is that the installation process is quite expensive.

Corner bathtubs

As the name shows, these are installed in the corner of your space. They are elegant options that are often used in large bathrooms because of their large dimensions. If you spend plenty of time in the bathtub and love to soak in the tub, then you will love this type of bathtub.

What you need to take measurements

How to take measurements of outer bathtub dimensions

In-Detail Guide on How to Measure Your Bathtub Inside and Outside

Apart from the effect it will have on the space, you need to know the outer bathtub dimensions. This will ensure that the bathtub will fit through the bathroom door.

Use the measurement to determine the length and the width of the tub and the alcove where you plan to install the tub.

How to measure inner bathtub dimensions

To measure the inner bathtub dimensions, use a measure to determine the inner length of the bathtub.

You should also measure the depth of the bathtub, which will be discussed in the sub-section below.

How to measure the depth of a bathtub

The depth of the bathtub is the interior measurement of the tub. To do this, you need to measure the deepest part of the tub to the overflow. This measurement is essential to know how much water the tub can hold.

How to measure the space you need for a bathtub

The measurements here serve as guidelines since there are so many models on the market, and the manufacturer makes bathtubs of different sizes. Regardless of the model you are looking to buy, you must consider the space’s size before purchasing.

If you are measuring an old bathtub to change it, then measurements should be done carefully to reduce the mistakes made. For example, if the bathtub you have is a drop-in option, some parts of the tub are not reachable, making it tricky to get the correct measurements.

So, you must measure the available space and do some estimation.

You must measure the width. To do this, ensure that you measure from the outer lip to the wall and include another inch to represent the part of the tub that is hidden from view.

For the length, measure wall–to–wall and include another inch on both sides to represent the bathtub parts that are not reachable.

The steps above are primarily for bathtubs that are alcove or drop-in models.

On the other hand, if you are installing a freestanding bathtub, it is easier to get, and the measurements can be obtained without needing to do any estimation.

Standard bathtub sizes

In-Detail Guide on How to Measure Your Bathtub Inside and OutsideThe truth is that there is no standard bathtub size. No dimension is viewed as the standard. Furthermore, as we have seen in this article, different manufacturers make tubs available in various sizes and styles. Therefore, we can only give a suitable size that is available on the market right now.

However, here are some measurements for the popular bathtub types:


Small: 50″ x 24″ 24.”

Medium: 60″ x 30″ 30″

Large: 72″ x 32″ x 30″


Small: 50″ x 30″ x 30″ x 15″

Medium: 60″ x 32″ x 18″

Large: 72″ x 32″ 20.”


Small: 50″ x 30″ 15.”

Medium: 60″ x 32″ 18″

Large: 72″ x 32″ x 20″


Small: 48″ x 48″ x 18.”

Medium: 60″ x 60″ x 20″

Large: 72″ x 72″ 20″

Final thoughts

So there you have it – how to measure a bathtub.

There are so many styles and sizes out there on the market. However, we hope that this post has provided concise information on the different types and how to get a good measurement for your bathroom.

Whether you are looking to install a new bathtub or are replacing an existing one, getting accurate measurements is very important.

Leave a Reply

Your email address will not be published. Required fields are marked *